Q IS Oi <:**%..%.. PEF'ARTMKNT (0 THE INTERIOR BUREAU OF SCIENCE A MANUAL OF PHILIPPINE SILK CULTURE CHARLES S. BANK'S (Prom the E-nlomologieal Sr.etion, Biological Laboratory Burma of Sciwcr, Manila, Philippine Islands) /^PcJ^Mtls hf ^ ^ \\ \\ h&m ISP / Order No. 406. THE HISTORY OF SULTJ. By Najeeb M. Saleeby. 275 pages. A complete History of the Moro People in Suhi, with maps and many translations from the original documents. Price $0.75, United States currency. Order No. 407. THE BATAN DIALECT AS A MEMBER OF THE PHILIPPINE GROUP OF LANGUAGES. By Otto Scheerer. and "F" AND "V" IN PHILIPPINE LANGUAGES. 141 pages By Carlos Everett Con ant. Price $0.80, United States currency. NEGRITOS OF ZAMBALES. Order No. 402. By William Allan Eeed. 62 photographic illustrations. 91 pages. An interesting ethnological study of the pygmy blacks of Zambales. Price $0.25, United States currency. Any of the above-announced publications may be ordered from the Business Manager, Philippine Journal of Science, Manila, P. I., or from any of the agents listed on the cover of this Journal. Please give order number. DEPARTMENT OP THE INTERIOR BUREAU OF SCIENCE A MANUAL OF PHILIPPINE SILK CULTURE BY CHARLES S. BANKS (From the Entomological Section, Biological Laboratory, Bureau of Science, Manila, Philippine Islands) MANILA BUREAU OF PRINTING 1911 M ca. V« on no 4 CONTEN T S. Page. Introduction 7 Historical 9 Experiments with Japanese silkworms 10 The mulberry silkworm. Bombysc mori Linn 10 The Japanese race or variety 10 The Bengal-Ceylon multivoltine race or variety 12 Introduction into the Philippines 12 The life history of the silkworm 13 The eggs — 13 Larvae and molts 13 Adults or moths - 19 The crossing of Bengal-Ceylon and Japanese silkworms 20 The eri or castor silkworm. Attacus ricini Boisd 24 Care of the eri silkworms 25 The future of the eri silkworm in the Philippines , 27 Wild silkworms , 27 Enemies and diseases of silkworms.— 28 The silk house 31 The mulberry. Morus alba Linn 35 Varieties or kinds of mulberry 36 Methods of propagation 36 The leaf - 38 The selection of cocoons for reproduction 39 Shipping eggs — - 41 Silk elaboration 42 Power reeling 42 Quality of the silk 43 Silk scouring 43 Jusi 43 The silk trade of the Philippines * 44 Commercial silk culture 45 Land 46 Silk house 46 Summary and conclusions 48 Appendix; Silkworm Importation Act 49 3 ILLUSTRATIONS. Plate I. Fig. 1. Newly hatched mulberry silkworms (Bombyx mori Linn.). 2. Pupating basket used in Japan; excellent for brood purposes. Plate II. Fig. 1. Mulberry silkworms 3 days old, previous to first molt. 2. The same after molting. 3. The same 11 days old, before second molt. 4. The same 12 days old, after second molt. Plate III. Fig. 1. The same 15 days old, before third molt. 2. The same 16 days old, after third molt. Plate IV. Fig. 1. The same 23 days old, full grown. 2. The same 24 days old, ready to spin. Plate V. Fig. 1. (A) Japanese white cocoons; (B) Philippine cocoons; (C) Bengal-Ceylon cocoons; all natural size. 2. Adult males and females of Bombyx mori, the mulberry silkworm. Plate VI. Japanese cocoons from which moths have emerged, showing discoloration of silk. No. 4 shows chrysalis inside cocoon. No. 8 shows chrysalis skin inside pierced cocoon. Nos. 13 to 10 show double cocoons made by two silk- worms and pierced at both ends. Plate VII. Nos. 1 to 4, female chrysalids, Bombyx mori; Nos. 5 to 8, male ehrysalids, Bombyx mori; Nos. 9 to 12, pupa skins left after moths have emerged from cocoons; Nos. 13 and 14, dead pupae of female and male slightly shrunken; from heated cocoons; Nos. 15 to 19, skins of silkworms shed inside cocoons when transforming to pupa. Plate VIII. Fig. 1. Pupating frame used in Philippines. 2. Section of same natural size, to show manner of supporting cocoons by guys of silk. 5 6 Plate IX. Adult male and female of Attacus ricini Boisd., the eri moth. Plate X. Fig. 1. Eri silkworms (Attacus ricini Boisd.) 1 day old. 2. Same 3 days old. Plate XI. Fig. 1. Eri silkworms, nearly mature. Natural size. 2. Same, greatly reduced, to show disposition on leaves of castor-oil plant ( Ricinus communis L. ) . Plate XII. Eri silkworms ready to spin. Natural size. Plate XIII. Baskets containing: Mulberry silk cocoons, dried banana leaves in which eri silkworms are pupating, and cocoons of latter from which moths have emerged. Plate XIV. Philippine tusser cocoons {Anthercca semperi Feld.), a wild species of silkworm. Plate XV. Fig. 1. Mulberry nursery under rain trees { Enter olobium saman Prain) at Bureau of Science, Manila. 2. Mulberry plantation at Bureau of Science. Plate XVI. Fig. 1. Philippine hand reel for the preparing of mulberry silk. 2. Berthaud power reel used in demonstrating silk reeling at Bureau of Science, now installed at College of Agriculture, University of the Philippines, Los Barlos, P. I. Plate XVII. Figs. 1 to 5. Sample weaves of cloth made from eri silk in India. Nos. 4 and 5 are dyed red and orange respectively. Nos. 1 to 3 are in natural color. Plate XVIII. Fig. 1. Philippine jusi weave. 2. Philippine silk cloth, unscoured. 3. Philippine silk cloth, scoured. Plate XIX. Plans of a silk house feasible for the Philippines and constructed of nipa, bamboo, and wood. This drawing is made to a scale of 1 to 100. Plate XX. Working drawings of hand machine for silk reeling. A MANUAL OF PHILIPPINE SILK CULTURE. By Charles S. Banks. (From the Entomological Section, Biological Laboratory, Bureau of Science, Manila, Philippine Islands.) INTRODUCTION. The Bureau of Science made the first attempt to import and to propagate mulberry silkworms in the Philippine Islands six years ago. Since that time various experiments have been undertaken in order to test the adaptability of these insects to the conditions of climate, altitude, food supply, disease, and natural enemies found in this Archipelago. Incidentally, limited data have been gathered as to the cost of: produc- ing a given amount of silk, the quality of Philippine silk, the probable demand for raw material in this country, and the best methods to be used in starting and maintaining a silk farm. Some of these results already have been given to the public 1 but only in a very general way, intended more to stimulate inquiry and to interest possible investors than to give a detailed account of the question from an experimental standpoint. It is the purpose of the present paper to collate all data thus far accumulated and to make them accessible to the person who desires to study the question with the end in view of entering upon the commercial production of silk. Many sources have been consulted on the general question and the experience of other writers has been utilized where conditions of which they wrote were found to be identical or similar to those in the Phil- ippines. A book by Percy 1ST. Braiue, 2 dealing with the subject from the standpoint of one who has devoted many years to silk culture in Ceylon, and from whom the greatest amount of help has been receive^ in the matter of introducing the Bengal-Ceylon silkworm here, has been freely used in the preparation of the present paper. 1 C. S. Banks, Silk Culture, Manila Daily Bulletin (1907), 16, No. 103, 31, 3 plates; Silk Culture in the Philippines, Phil. Agr. Rev. (1910), 3, No. 3, 186, pi. VII. )- v * 2 The Cultivation of Silkworms, Colombo, 1904. 7 A thorough theoretical knowledge, as well as a predilection for the work; is necessary for the successful propagation of silkworms, and those engaging in the industry must also be prepared to learn from daily experience in the silk house. The Filipino possesses an infinite patience in small things and is quick to learn by seeing them done, so that he would seem to be well qualified for engaging in the business under discussion. The women and children are available for the indoor labor and the men for mulberry cultivation. This would assure the success of silkworm raising in almost any portion of the Archipelago. Individuals who undertake this work should always remember that "cleanliness, regard for detail, and perseverance," form the keynote of success and those who are not willing to devote intelligent, constant care to the oversight of the process should hesitate before investing money or planting mulberry trees. The original, wild silkworm, Bombyx mori Linn., is supposed to have spread from somewhere in western China and indeed it is said that even at the present day it may be found there. Centuries of care have devel- oped certain well-marked strains with the following characteristics : Variation in number of broods, fecundity, shape and color of cocoons, quality and quantity of silk, and immunity from or susceptibility to dis- ease, although the last has more to do with neglect or carelessness in methods than to an intentional process of breeding. Of all these cha- racteristics none is more remarkable from the bioLogie standpoint than that of the variation in the number of broods. Most insects yield no more than two broods a year, very many only one, and, where three or nior' 1 occur, it will be noted that the insects are either strictly parasitic or else find their source of food supply in some artificial condition created by man. Such is the case with the house fly, the mosquito, human and animal parasites, and grain and sto red-food pests. Insects which live under conditions that lack what we might term man-made uniformity and protection, find the food supply too limited, or other natuial influences too rigorous to insure a multiplicity of broods during a year. With many, producing but one or two broods a year, the so-called hibernation period is passed either as larva, pupa, or adult. A number of wood-boring beetles pass one, two, or even more years feeding within the tree; other insects, such as the wheat midge, the cod- ling moth in America, and the ylang-ylang moth (Attacus ail ax Linn.) of the Philippines, pass the longest portion of their lives in the pupa. House flies in temperate climates winter as adults. Remarkably few species of insects spend the longest period of their life cycle in the egg. The original, wild race of the silkworm is undoubtedly among these and also the monovoltine race, cultivated by the Japanese and described below. 3 However, the silkworm, by taking precocious individuals and breeding from them, has been brought, in certain regions to the point where it will produce from two to nine generations m a year. HISTORICAL. We are indebted to the early missionaries for the first attempts at the importation of silkworms and the mulberry into these Islands. Jose Montero Vidal in Ids El Arehipielago Filipino (1887) says: The mulberry {Morns alba Linn.) has existed in the Philippines since 1593 in which year the Jesuit Father Antonio Sedefio planted great numbers in the Visayas. Afterwards, in 1780, the Agustinian Missionary, Father Manuel Ga- liana, sent this plant from China and at the time remitted the silkworm eggs (seed). The Royal Economic Society of the Friends of the Country endeavored to promote this industry but the agriculturists of those days never lent them- selves willingly to the growing of the silkworm, because of the great care which it demanded, and now it is entirely abandoned, a fact due also in a measure to a lack of financial backing. During the time of Governor-General Basco y Vargas, there existed in the Camarines four and a half millions of (mulberry) plants. Covantes, in Episodios Ilistoricos de Filipinas (1881), adds: Father Sedeno, knowing the revenues which China derived from silk, made large plantings of mulberries for feeding the worms that produce the silk, to the end that the country might have the advantage of this richness; and con- sidering the irrigation of the land as inseparable from all that pertains to good agriculture, taught also how easy it Avas to take advantage of it. Having made this advance and placed the industry at the height demanded by social conditions of the time and having noticed that the Indian suffered much from hick of* proper clothing, especially at the time of the northeast monsoons, and moreover being opposed to their going practically naked, he made looms with his own hands, taught them to weave cloths, and gave them thread of various colors, dyinl with plants of the country. The Indian, better and more abundantly fed, better protected from the in- clemencies of the weather and liking these innovations very much, followed most willingly his true civilizer, Father Sedefio. The silkworm develops very easily and repeated experiments prove the pos- sibility of getting two or three crops of cocoons [a year J. The species which lives upon Tangantangan {h'icinus communis Linn.), the castor plant, resists storms and typhoons and its silk, although less fine, lias assured value. Father Pedro Chirino says of Father Sedefio: Me was the first to burn lime there, he made the first tiles, he built the first house of stone, lie was desirous that silk be cultivated in the Philippines, because in this way, having the industry already within the country, the money returns from it could be used at home instead of going to China. 3 This insect remains from ten to ten and a half months in the e^, eighteen to twenty days in the larva, ten to twelve days in the pupa, and three to four davs in the adult stage. 10 With this end in view he planted mulberries, investigated other things and even went so far as to teach the Indians to sew according to European methods. From the year 1780 to the beginning of the 20th century, we hear no more of attempted introductions of silkworms into the Philippines. EXPERIMENTS WITH JAPANESE SILKWORMS. In the latter part of 1901, I had an opportunity to study the methods of silk culture prevailing in the Imperial Experiment Station in Tokyo. After a conference with Professor Kuwana, entomologist at the station, I was convinced that a trial of silkworms in the Philippine Islands would be well worth repeating with a view to encouraging their introduc- tion and culture on a large scale. As there were mulberry trees growing in the Province of Batangas and in Manila, all we lacked was a sufficiently large planting of trees to insure an abundance of leaves when the eggs should arrive and begin to hatch . Returning to Manila, I learned that Mr. W. S. Lyon, then of the Bureau of Agriculture, had written for eggs which he expected early in 1905; and that in anticipation of their arrival he had sometime previously transplanted cuttings from mulberry trees near the laboratory building of the Bureau of Science, to the experiment station at Singalong, where the young plants were doing exceedingly well, under irrigation. On February 14, 1905, Mr. Lyon's eggs arrived from the Japanese Experiment Station. He gave me approximately one-half of the lot, the remainder having been turned over to Don Vicente D. Fernandez for experiment at his hacienda in Nasugbfi, Batangas. THE MULBERRY SILKWORM. Bombyx mori Linnaeus. THE JAPANESE RACE OR VARIETY. The two principal races of silkworms produced in Japan for com- mercial purposes are the monovoltine, which produces one generation a year in the spring and the bivoltine, giving two crops, one in the spring and the other in the autumn. In the year 1905 attempts were made to propagate the mcmovoltine race of Japanese silkworms in Manila, but the results were not satisfactory for several reasons, the chief of which is the decided difference in climate between the Philippine Islands and Japan. In the latter country the silkworm eggs hatch in early April and by the middle or end of May the insects will have finished their life cycle, laid their eggs and died. These eggs are collected by agents of the government, examined baeteriologieally, assorted, placed on uniform sheets of specially prepared cardboard and then packed in air-tight receptacles either of wood or tin, and buried in pits or placed in special cellars. They remain for a period of approximately 10 months in an inert condition, suffering practically no shrinkage. A few weeks before the time when they should hatch they are taken from the packages, reexamined and distributed to the individual silk raisers, who either place them in artificially heated rooms if the weather is cool, or else simply leave them at air temperature if it is warm. The period of 11 hatching is practically simultaneous all over the silk region and within 45 or 50 days from hatchings the whole crop has been disposed of for the year. # Should anything like drought or unusually cold weather occur to retard the mulberry trees in putting forth their foliage, the eggs are kept in cold storage to allow further time for the developing of their food supply, but it occasionally happens that a whole crop will be lost in a given district where the leaf supply fails. Probably in no other country, with the possible exception of China, has the silkworm been so thoroughly artifieialized in its habits and manner of develop- ment as it has in Japan and, therefore, this, insect in the latter country has suffered from the attacks of all the principal diseases to which it is subject. As it yields only a single crop a year, any extensive attack of disease among the silk- worms means a loss of one year's efforts on the part of the grower. Undoubtedly, Japan produces the best grade of silk in the world, but any country where more crops could be raised in a given time would have an advantage, provided its silk were not materially inferior to the Japanese product and the grower had no diseases to contend with. In the year 1905 in our experiment with Japanese monovoltine silk- worms, we found that the cocoons, moths, and eggs produced in Manila from silkworms fed on the Philippine mulberry were all that could be desired, both as to quality and quantity. We met our first obstacle when we undertook to dispose of the eggs until the time for the next generation. Ample facilities were at hand for keeping them in cold storage, but so doing would prove nothing beyond what was already known from years of experience elsewhere. To be of practical advantage it was necessary to know whether Japanese eggs could be kept at air temperature for 10 months in the Philippines without deteriorating and two experiments were undertaken to determine this. A part of our crop of eggs was put into cardboard boxes for protection from dust alone, while another was placed in sterile Petri dishes and then in sterilized, moderately tight tin boxes. All of these batches of eggs were left at room temperature in the laboratory. They were observed from time to time for signs of shrinkage or the growth of molds. Those kept in cardboard boxes were soon found to be infested with a tiny psocid which ate the shells and destroyed the contents of the eggs. Those kept in tin boxes began to mold during the rainy season in August and although they were frequently cleaned by the aid of small camel's hair brushes, they, like the eggs kept in the Petri dishes, began to shrivel and by the middle of January gave every evidence of desiccation. None of these eggs, some 70 batches in all, hatched nor showed any sign of incubation. They had all been laid upon sterilized filter paper, and were healthy at the time of being laid. The conditions under which eggs of monovoltine silkworms would be kept at any place outside the city of Manila would be decidedly less favorable than those under which the above experiments were carried out, and so the chances of successfully carrying eggs over for 10 months would be fewer at such places. 12 Therefore, it would be very unwise to encourage the importation of Japanese monovoltine silkworms except for purposes which will be in- dicated below. THE BENGAL-CEYLON MULTIVOLTINE RACE OR VARIETY. The early experimental work with the Bengal race of silkworms in Ceylon demonstrated that there it regularly produced six to seven genera- tions or crops in a year. Therefore, when the Japan race had not proved successful in the Philippines, we turned to Ceylon for a silkworm which already had demonstrated its prolific nature and its adaptability to a continuously warm or tropical climate and which, furthermore, had pro- duced an excellent quality of silk. Mr. Braine had been most successful in producing what has now been des- ignated the Bengal-Ceylon race and through his courtesy the Bureau of Science obtained cocoons of four of his most promising types, namely, the golden-yellow, pale yellow, white, and dwarf white. The golden-yellow has nourished best under the influence of the Philippine climate. Thirty-five complete generations, an average of nine a year, have now been grown by us. Two other types slowly reverted to the yellow, but occasionally we obtain white cocoons, although there has been no attempt to regain them since they disappeared, inasmuch as all gradations of color may be found among the golden-yellow types, and, by a simple process of selection through three or four generations, they will produce uniformly colored cocoons of any desired tint of yellow. Therefore, the best results have been obtained with the Bengal-Ceylon race in Manila, while experiments in the crossing of this race with the Japanese monovoltine white, have produced what we tentatively call a Philippine hybrid, or race. Of course, as it is a cross between individ- uals of the same species, it is technically not a hybrid. INTRODUCTION INTO THE PHILIPPINES. The Ceylon silkworms were received in Manila on March 11, 1907. The cocoons had been prepared for shipment by Braine in the following manner: A dozen to fifteen of them were strung together upon a piece of sewing thread passed through one side near the middle of the cocoon in such manner as not to pierce the living chrysalis within. The ends of the thread were fastened to a strip of wood held within a small ventilated box, thus enabling the moths to emerge in the box without damage. When the package reached Manila the moths had emerged, paired, and laid a plentiful supply of eggs upon the blotting paper placed there for that purpose, and many of the young caterpilars had already hatched. The varieties were kept separate and within two days after their arrival the eggs had all hatched. The caterpillars were cared for at the laboratory of the Bureau of Science for a few days and were then transferred to a specially built house at the Singalong experiment station distant one-half kilometer, where they could be continuously under the charge of the entomologist of the Bureau of Science and at the same time be subject to the same conditions which would prevail in any part of the Islands where they are to be grown. 13 A Filipina girl was put in charge and several Filipino workmen instructed as to the method of caring for the trees, gathering the leaves, and cleaning the trays and the silk house. The work was continued at the experiment station until January, 1910, when a suitable, permanent silk laboratory was completed at the Bureau of Science. THE LIFE HISTORY OF THE SILKWORM. THE EGGS. The Bengal-Ceylon silkworm remains in the egg stage, in Manila, for from 8 to 9 days, thus surpassing all known varieties of this species in shortness of egg-period. When these insects came to Manila they were producing not more than seven generations a year, because the feeding as well as the egg-period had been lengthened in ,Ceylon during the told weather, the one a natural contingency, the other partially artificial, as they were bred in a cooler upland region, Peradeniya being about 520 meters above the sea. The difference in temperature in Manila between the mean of the cool and warm seasons is so slight that the silkworms are practically always under the influence of an elevated temperature. The results of this con- dition can easily be seen in the continued production of nine generations a year for the entire four years since their introduction into the Islands. Uniformity of hatching. — It would naturally be supposed that in changing from a monovoltine |o a polyvoltine habit, a condition of uni- formity of hatching would be almost impossible to secure, even after several scores of generations. Especially would we expect, that in pass- ing from seven to nine generations a year there would be many cases of retarded incubation in each batch of eggs and consequently a con- dition would obtain where continuous hatching, successive moltings, and hence continuous pupations, would take place, but this has not been our experience. The young silkworms begin their emergence from the egg early in the morning and by noon all are out. LABV^E AND MOLTS. It has been the custom in the entomological laboratory of the Bureau of Science to allow each of the moths to lay her eggs upon a disk of filter paper. These disks are pasted to the hatching tray so that they will not be blown away or confused. The larva (PI. I, fig. 1) measures 2.5 millimeters in length when it emerges from the egg. It is then very dark gray, almost black, because of the dark brown head-case and the multitudinous spines which are dispersed regularly over the body. The silkworms, as soon as hatched, wander a few millimeters away from the egg and remain in a quiescent condition for" three to four hours. They then begin to show further signs of life and activity by lifting the 14 head and moving it from side to side. As soon as this occurs they should have their first food, as much, if not all of the silkworm's future vigor depends upon the first feeding. The tenderest, young, green leaves which have become nearly expanded and are still of a very pale hue and which are taken from the tips of the mulberry shoots should be given at this stage, but those which are not as yet unfolded should be avoided. The leaf is placed over the filter paper in such a way as to be within reach of the young larvae. The silkworm, in all stages of its growth, probably is one of the most helpless of domesticated animals, and it is especially dependent upon the person taking care of it while it is very young. It will hardly move twice its own length in search of food, and unless the leaf is placed directly upon it, the chances are that it will starve. Once the food is within reach, every young silkworm will soon climb up on it and begin feeding. When this transfer has taken place, the attendant removes the leaf to a paper tray, so placing it that the leaf will be beneath the silkworms. The effect of their feeding will be noted very quickly upon the leaf, as at first they only consume one epidermis and then feed through to the other. If the leaf is tender and succulent the entire sub- stance, except the veins, will be consumed before it is necessary to change. However, if the leaves show any signs of being too dry for the larvae, they should be replaced by fresh ones laid whole upon the old. It is seldom necessary to transfer any silkworms from old to new leaf, as they readily go up themselves. If such a transfer must be made a small, clean camePs hair brush, or other similar instrument alone should be used for the purpose. The silkworms should never, on any pretext, be touched with the fingers, and it is seldom necessary to touch- them with anything. In lieu of a camePs hair brush, a very delicate pair of fine-pointed pincers made from bamboo may be used, provided the attendant is expert enough to seize the larva without, in the least, pressing upon it. Silkworms in the first stage require but little care other than to be well provided with the proper quality of leaf. The amount of excre- ment is «mall and very dry, so that the cleaning of the trays is ex- tremely easy. The silkworms remain in the first stage an average of from three to four days, during which the larvae increase to 2.5 times their length at hatch- ing. They prepare for the first molt at night and begin molting in the early forenoon. The signs are a cessation from feeding, a general, appearance of fullness, an elevation of the forward third of the body, a drawing together of the forward three pairs of legs, the assuming of a sphinx-like attitude, and the extremely small size of the head as com- pared with the rest of the body. This latter is one of the most notice- 15 able features of a silkworm preparing to molt. The explanation is as follows: The head is composed of a single segment of chitin, which hardens as soon as the insect emerges from the egg and is exposed to the light and air. The head covering does not stretch with the rest of the body covering and hence at the time of molting is comparatively very small. The skin of the body is more capable of expansion, but is not elastic enough to keep pace with the growth of the internal portions of the caterpillar. The necessity for molting at certain regular periods of the insect's growth is therefore apparent. (PI. II, fig. 1.) First molt. — In the act of molting, the old skin of the silkworm splits along the middle of the back, beginning at the head, and the insect slowly withdraws its six true and eight false or abdominal legs. The old skin is left just behind the larva, much crinkled and adhering to whatever the insect was resting upon. The head case is forced off gradu- ally by inflation of the new head skin and by side to side motions of the insect itself. The newly emerged caterpillar is much paler than before its molt and the head covering is of a decidedly light buff color. Within two or three hours it becomes dark and very hard. The cater- pillar then is in condition again to begin feeding. Second stage. — The best time for transferring the young silkworms to the regular feeding trays (see page 34) is after the first molt and before feeding. The new tray is placed over the one upon which the young silkworms are lying in such a manner that its meshes will touch them. Young leaves cut crosswise into strips 2 centimeters broad are then evenly sprinkled on the new tray over the parts below which the silkworms are. Within two minutes the silkworms will begin to come up through the meshes and commence feeding. 4 The second stage lasts for from three to four days, during which time the silkworms eat an increasing amount of leaf, being fed regularly every three hours from 6 in the morning until 9 at night. In our laboratory work in Manila we have never practiced feeding silkworms during the hours from 9 in the evening to 6 in the morning, but in actual practice it would undoubtedly be better to do so in all stages. The silkworms, when ready to molt the second time (PI. II, fig. 3), 4 It is one of the cardinal rules of silk culture that mulberry silkworms should always be fed in this manner. It is cleanly, all refuse is left behind; it is rapid, there is no necessity for taking the silkworms off a tray one by one, a process not only tedious, but sure to injure the delicate creatures; it is sanitary, the silkworms have the advantage of a tray in which there, is always an abundant circulation of air and their excrement falls through to one provided for this purpose after the old tray is removed; and, finally it enables the attendant to discover quickly any silkworms which from debility can not come up and which, therefore, should be separated from the healthy individuals and watched for signs of illness. 16 measure 12 to 14 millimeters in length and have the characteristic markings of the species, although the pattern is small. 5 Second molt, — The second molt, like the first and all succeeding ones, is heralded by a cessation of feeding and the comparatively small head case. Experience very soon teaches the careful attendant just how to proceed, and she makes a corresponding disposal of her leaf, giving directions to the leaf gatherer as to when to stop cutting and preparing a fresh supply, according to the appearance of the caterpillars. The second molt does not differ in any respect from the first. (PL II, fig. 4.) After each molt the silkworms require a greater and greater amount of tray surface. Table II, page 17, shows the maximum number of silkworms to a given area at each stage, and it should be followed by the practical grower who must constantly bear in mind the danger of overcrowding, which is one of the most serious faults in sericiculture and invariably leads to losses which increase year after year. It has been the most fruitful source of the various diseases encountered by the silk growers of Europe and which, in some years, have annihilated whole crops of silkworms. Third stage. — At the beginning of this stage the silkworms measure 2.5 centimeters in length; (PI. Ill, fig. 1.) they are much paler than in the preceding and may safely be picked up with bamboo pincers without injury, provided a due amount of care is exercised. The length of time in this stage varies from 3 to 4 days, and the leaf fed to the insects need not be cut as finely as for those in the second, in fact many practical silk growers believe that silkworms in the third stage, if not even in the second, should be fed whole leaf. 6 Only fully opened, but tender leaf should be fed the silkworms during this stage. A safe rule is : "Age of leaf to age of silkworm." Third molt. — The third molt occurs 4 to 5 da}^s after the second and, so far as the life of the caterpillar is concerned, marks a point about half-way from egg to cocoon. The same signs of molting are evident and the same care should be taken not to disturb the insects while they are in their "sleep." Food offered to them is doubly injurious as it is a source of irritation to the silkworms and a waste of effort on the part of the attendant (PL III, fig. 1). Fourth stage. — During this and the succeeding stage, the silkworms 5 That the caterpillar's head does not grow during a given stage is shown by placing a newly molted specimen in alcohol and comparing it with others of the same stage when they are ready for the succeeding molt. If this fact is borne in mind, and a study of the molted head cases made, the stage through which they are passing can readily be told by looking at a given tray of silkworms. 6 It has been the experience in the Bureau of Science that they do not waste as much leaf when cut as when it is fed whole, and for experimental purposes it is much easier to calculate the amount required. 17 may safely be fed fully matured leaf; not hard, dry leaf which is on the verge of dropping from the plant, but fully expanded, dark-colored, glossy leaf of a rough feel, but which is free from sand, dust, and mold. As mature leaves are usually found near the base of the plant, they are also more likely to be sandy, due to rain spattering. All such should be cleaned thoroughly before being fed to the silkworms. Nothing will produce digestive disorders, especially diarrhoea, in silkworms, quicker than sandy or dusty food. (PL III, fig. 2.) The silkworms in this stage require slightly more than double the space previously needed, but care should be taken not to feed them for two or three hours after they have passed the molt, in order that they may recover from its debilitating effects. Fifth stage. — In this, the last stage previous to the chrysalis, the silkworms measure from 7 to 8 centimeters in length. Their bodies are plump, the skin having almost no folds and being buff-grayish white, turning to a translucent yellow a day or two before they begin to spin. They feed continuously and with great voracity, but the change of color indicates a previous cessation from feeding and, therefore, no more leaf should be given them. Silkworms need 30,000 times their weight of food from hatching to cocoon. They consume two-thirds of this amount, the other third being waste, so that 35,000 to 40,000 larvas, from 30 grams of eggs, require leaves as follows : Table I. Stage, Kilograms. First 5 10- 15 40- 60 120-160 700-800 Second Third Fourth __ _ ___ _.._ Fifth The above table shows that of the total of 1,000 kilograms one-half is consumed during the latter days of the last stage. The space required for 35,000 silkworms is as follows: Table II. At hatching After first molt After second molt_ After third molt After fourth molt _ in square 1 4- 8 16 32 60 102839- 18 The more space allowed the silkworms the more silk will be produced. The same rule applies here as in fruit production. Careful pruning of trees or vines increases growing space and gives more and larger fruits. Careful spreading of the silkworms over sufficient space allows more room for development and consequently gives larger silkworms (PL IV, figs. 1 and 2) and larger and better cocoons. Spinning. — The insect, apart from the periods of molting, is most susceptible to accident during spinning. There is great risk of losing many caterpillars if they are not properly cared for. A silkworm first indicates that it is about to spin by ceasing to eat, protruding its head, and beginning to reach around as if looking for something. The body grows translucent, and careful examination shows that the caterpillar extrudes from the mouth a small, tongue-like organ from the tip of which a tiny thread of silk is attached here and there to the surface upon which it rests. The instinct to mount, which is manifested when new trays of fresh leaves are placed over a tray of silkworms, is also shown when they are about to spin. In a short time after the first indications of this desire, the silkworms begin to crawl away from the tray and to climb up the sides of the racks. They must then be provided with a spinning place. Various devices may be employed. Bundles of non-resinous twigs tied together and placed vertically over the trays in columns like the aisles of a Gothic church make excellent spinning places. Clean rice-straw, cogon, taldhib, 1 or other similar substances, may be put into bamboo baskets and the silkworms carefully picked from the trays and placed in these. Care should be taken to put them well down into the mass of the straw, so that they may spin with as little waste of silk as possible. An excellent device used largely in Japan consists of a round, flat bamboo basket in which is placed, in spiral form, beginning at the center, a long strip of straw braid, the width of the braid and the spaces between the turns of the spiral being about the width of a cocoon when completed. Several hundred cater- pillars can spin in such a tray and these are especially desirable for silkworms to be used for reproduction, as more perfect development of the chrysalis is possible. (See PI. I, fig. 2.) Various other arrangements for spinning (PI. VIII, figs. 1 and 2) will suggest themselves to the alert silk grower and his chief object should be to get perfect cocoons with a minimum amount of web or floss. The caterpillar, after finding a suitable spinning place, evacuates the alimentary canal and begins to throw out silken lines in various direc- tions to serve as guys for building the actual cocoon. When these are 7 Cogon and taldhib are species of large, coarse grasses growing wild in the Philippines. 19 completed and the dimensions of the cocoon thus laid out, it begins the real work of cocoon making. The motion of the head is in a path like the figure 8 and the thread is continuous until the cocoon is complete. One end of the latter is woven more loosely in order to enable the moth to emerge at the proper time. Within three to five hours after beginning the cocoon, the caterpillar is hidden and within twenty-four hours the work is completed. The larva changes to a chrysalis on the first or second day thereafter and then the cocoon may be heated or other means of killing the inclosed insect employed, if the cocoon is to be used for silk. ADULT OR MOTH. The adult (PL V, fig. 2) emerges on the 11th or 12th day after spin- ning and about nine or ten days after the transformation to the pupa. The moth pushes aside the strands of silk in the weaker, more loosely woven end of the cocoon, by aid 'of a secrection which it exudes upon coming from the pupa-skin inside the cocoon (PL VI). The act of emergence is quite brief if the moth is healthy. It is moist upon coming out, the wings are yet small and folded, and the abdomen is long and dis- tended with fluids. The digestive tract is soon evacuated, the wings expand and dry, and the insect, if a male, begins to search for the female. The latter remains quiet after becoming dry and perfect, but extrudes from the last abdominal segment a somewhat complicated ap- paratus which is slowly waved from side to side as a means of dispersing the alluring odor. Copulation. — This act will usually be accomplished immediately upon emergence if the males are allowed access to females, but it is much better for the attendant to take measures to defer it until the moths are throughly dry. It should continue for about 2 hours in order to insure proper fertilization of all the eggs, and one copulation, if of proper length, is sufficient for a single female. A male may be used to fertilize 8 or 9 females, but it is decidedly better and more economical of time to have at least one male to every two females. If there be too few males, some of the females may begin egg-laying before being fertilized and of course such eggs are worthless. Egg laying. — The females begin egg-laying very shortly after copula- tion. A healthy insect will deposit her eggs over a limited area, in a single layer carefully placed, the ova lying flat upon the surface. The last eggs should be laid within 24 hours of the first, but a healthy, though slow, insect may take a slightly longer time. The egg papers are marked with the date and put away until the time of hatching, ten days thereafter. 20 THE CROSSING OF BENGAL-CEYLON AND JAPANESE SILKWORMS. Bengal- Ceylon silkworms produce nine generations per annum in the Philippines. The cocoons are golden-yellow, large in the middle and* rounded at both ends, one of which is always slightly more acute than the other. (PI. V, fig. 1, row C.) The Japanese white silkworms, with which we have experimented, produce a single generation a year. Their cocoons are constricted in the middle and bluntly round at each end. (PI. V, fig. 1, row A.) The crossed races produced at the Bureau of Science were at first of four classes; yellow, pale yellow, yellowish-white, and white, but after twenty-five generations they all are practically white and of the shape of the Bengal-Ceylon variety. (PI. V, fig. 1, row B.) It is not necessary to go into the details of our breeding experiments here as practically the same work was most admirably done by Toyama 8 who has dis- cussed Mendel's law of heredity in this connection, in a highly interesting and scholarly paper. The blend finally produced will be termed by us the "Philippine Pace of Silkworms," and I am confident that it will continue, as it has now existed for more than twenty- five generations. We still have retained the pure Bengal- Ceylon variety, and have both kinds for distribution. 8 Bull Coll. Agr., Tokyo (1906), 7, 262-386. 21 ft., es J* § § s SQ S 1 1 OOoj' ! ! 00 00 CO 00 rH 05 CX3 O CT> TT< CO •* CO CO TP CO 1 1 M M "T H 'O 1 1 go « ! ! ! 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CO CO lO s OS CO CO CM a S3 as •-5 CM CM be S3 O CO ft co > o CD Q OS O OS OS OS CM c3 00 c? a C S3 CM ft a> CO O O CO o o OS 00 s •-5 CM Eh 00 ft 00 CM 3 •-5 CO 00 ft cd co o CM a O U OS CO iO Tt< CO -rj* rti 00 O) l> t(( (O •-5 -3 co O CO CO OS CO iO CO to ^ -< t-5 i-, < o y, fc § Tji rf CO CO COCOTt<^cOCOCOCO CO rH O OS 00 00 00 r— I iO iO CM © CO CO CO r*-< t-5 < cud te p. h "1 M 2 O OS Os CO OS 00 OS OOSQOOOOSI^OSOS OS CO t* O rH fc, <| ^ H, rH rH CM Ttl I rH CM OS 5? ft *»" -* § c S3 57 o « -H \ [^ iO 00 1^ iO iO * ft ^ 3 3 57 o ^ « » 3 ^ fH & & H, r-, ft "^ 5T o co O Ph -< S (N M ■* iO (O N £ ft ** --; a) ° ^ co O i-H rH CO CO !^ 0SOrHCMC0Tj,000 eri cater- pillars: First day 2; second 4; third 6; after first molt 10; after second 20; after third 35; after fourth 50. 26 These caterpillars are at no time as inert as the mulberry silkworms and at the time of spinning are extremely prone to wander over every- thing around them in search of a place to spin. At one time in the laboratory in Manila, owing to carelessness on the part of the attendant who failed to provide suitable spinning quarters, several thousand cater- pillars wandered over racks, trays, tables, chairs, walls, and screening, and many were drowned in the water under the legs of the racks. The most satisfactory substance on which to allow this variety to spin consists of finely shredded, dry, banana leaves, or dried cog on (Im- perata exaltata Brongn.) or talahih (Saccharum indicum Linn.) leaves arranged in a basket about 15 centimeters in depth and as large as a tray. In preparing any material of this nature for silkworm nests, care should be taken to see that it is clean and free from ants, mice, and such vermin, otherwise havoc may result. As the cocoons can not be used until the moths have emerged from them, all cocoons of this species should be carefully placed in trays until after that time. They can then be dried and packed or otherwise disposed of. Before the moths have emerged, the cocoons should be laid in rows with spaces between each two rows of, say 5 centimeters, so as to allow of proper room for emerging without injury. It is best to remove moths to other trays or to breeding cages made of wire or mosquito netting, where they can hang by their feet and properly develop their wings, after which they are in condition for mating. The mature insects of this species lay their eggs in a lunate mass, row upon row r , projecting from the surface upon which they rest, but the eggs are placed side by side so that the young caterpillars can easily hatch from them. Moths, after egg laying, may be fed to poultry, or else killed and burned, or buried. They should under no circumstances be allowed to lie around near the silk house where they would attrack ants or other vermin, and decaying, give rise to danger of disease among the silk- worms. Eri cocoons will keep indefinitely if they are dried thoroughly in the sun after the moths have emerged. They should be kept dry, and in the rainy season should be watched to prevent the attack of molds or mites. The ideal course would be to spin the material into yarn as quickly as sufficient quantities accumulate. The Bureau of Science recently has acquired two machines, one for reversing the eri cocoons and throwing out the chrysalids and caterpillar skins, the other for spinning the silk. The object of reversing the cocoon is to obtain a silk free from the debris left by the moth and thus cleaned and of better quality. These machines were in operation at the Carnival of 1911, together with samples of the work done with them. Even after learning the theory of eri silk spinning, good results or even fair ones are only obtained by months of practice in the effort to spin fine threads of a uniform size and free from waste particles and knots. n THE FUTUBE OF THE EEI SILKWORMS IN THE PHILIPPINES. In India the silk from this insect is woven into cloth by the natives. It is called eri or eria 12 and lasts practically a lifetime. It is probable that, once started in the Philippines, its cultivation and use for fabrics would be popular not only among the Christian Filipinos, but also with the mountain tribes and the Moros, all of whom use large quantities of cotton in making the fundamental articles of dress as distinguished from mere ornaments. Eri silk, because of its lustrous appearance and durability, would find a ready sale among Americans and Europeans for hangings, upholstery, and even for heavy dress goods, as it can be dyed any color. If dyed to resemble pongee, which is produced from the wild tusser, Anther Demand for silk, in Philippines, 45 ; in United States, 47. Devices for spinning, 18. Diospyros discolor, 27. Dirty leaf, effects of, 17. Diseased silkworms, where to send, SI. Diseases of silkworms, 28. Disks, filter-paper, for eggs, 13. Disposal of cocoons, 42. Distances for planting trees, 46. Distinguishing marks for male and female cocoons, 40. Distribution of eggs, 48. Doors for silk house, 34. Double doors, advantage of, 34. Drainage, necessity for, 35. Drainage of nursery beds, 37. Dust, dangers from, 32. Duty on silk, 47. E Earthen floors in silk house, 33. Egg-laying, eri moth, 26 ; manner of, 19 ; time of, 19. Eggs, care of, 41 ; dating of, 41 ; hatching of, 41 ; how properly laid, 41 ; selection of, 41 ; shipping of, 41 ; transmission by post, 41. Egg trays, 41. Emergence, manner of, 19 ; time of, 19. Enteritis, 29. Enemies of silkworms, 28. Eria, 27. Eri cocoons, disposal of, 26. Eri moth, disposal of, 26. Eri moths, egg-laying, 26. Eri silk, character of, 25 ; spinning of, 25. Eri silkworm, 24 ; care of, 25 ; future of, in Philippines, 27. Eri silkworms, number to tray, £5. Experiments with Japanese silkworms, 11. 51 Feeding, hours of, 15. Fifth stage, 17. Filipino, adaptability to silk culture, 8. Filipino teachers, training of, for silk cul- ture, 48. "Filipino" silk, price of, 47. Filter paper, used for eggs, 40. Flaccidity, 29. Flacherie, 29. Flies, 28. "Floss and twisted silks," 44. Floss, removal from cocoons, 40. Food plants of wild silkworms, 27. Forceps, bamboo, 14. Formulas for silk scouriug, 43. Fourth stage, 16. France, reports on silk sent to, 43. Furniture for silk house, 34. G Galiana, Father Manuel, mentioned, 9. Gathering leaf, 39. Gattine, 29. Gauze, wire, for silk house, 33. Gekkos, 28. General cleaning <5f silk house, 34. Germicides, use in silkworm diseases, 30. Grass, advantages of, around silk house, 32. Grasserie, 30. H Handling of silkworms, 14. Hand reel for silk, 42. Hatching, uniformity of, 13. Head-case of caterpillar, IB. Hongkong silk, price of, 47. Hornets, 28. Hours of feeding, 15. Hybridizing, 20. I Ichneumon flies, 28. Importation of silkworms prohibited, 49. Income from silk, gross, 47. Inquiries, to whom sent, 48. Insects, domestic, hibernation of, 8. Japanese white silkworms, 20. Japan, silk from, 44. Jusi, 42 ; its character, 43. Labor, cost of, 46. Land for silk culture, 46. Law referring to silkworms, 49. Leaf, 38 ; amount fed, 24 ; method of plac- ing in trays, 15 ; methods of gathering, 39 ; quality of, 17 ; yield per hectare, 47. Legislation in interest of sericiculture, 49. Lifi-histories, tables of, 21, 22, 23. Lizards, 28. Lyon, W. S., procures silkworms, from Japan, 10. soil for, 35 ; introduction M Mabolo, 27. Machine, reversing, for eri cocoons, 26 spinning, for eri silk, 26. "Manufactured" silk, 44. Manufactured silk, importations of, 45. Measures for invigorating breed, 39. Melastoma, food for wild silkworms, 27. Mice, how to keep out of silk house, 33. Molting, how performed, 15. Monomorium floricola, 28. Monovoltine silkworms, 8. Morus alba, 35. Moth, emergence of, 19. Mulberry, 35 ; drainage of freedom from disease, 38 into Philippines, 9 ; methods of propaga- tion, 36 ; Philippine varieties of, 35 ; planting of, 36, 37. Mulberry leaf, yield of, 46. Mulberry silkworm, Japanese race or vari- ety, 10. Mulberry trees, number to hectare, 46 ; production of leaf, 46. Multivoltine silkworms, 12. Muscardine, 30. N Newly hatched silkworms, handling of, 14. Nipa, use in silk-house construction, 32. o Overcrowding, dangers of, 35. Parallel breeds of silkworms, 39. "Partially manufactured" silk, 44. Pebrine, 28. Pests, how to kill, 32. Petroleum, for killing pests, 32. Philippine silk, price of, 47 ; quality of, 47. Philippine silkworms, freedom from disease, 31 ; production of, 20. Picking of mulberry leaf, 39. Pincers, bamboo, 14. Planting mulberry, 37. Power reeling, 42. Poultry, dangers from, 34. Prevention of dust, 32. Principal diseases, 28. Protection required by silkworms, 31. Pruning mulberry trees, 37, 38. Q Quality of leaf, 17. Quality of silk, 43. Quantity of light in silk house, 32. R Races of silkworms, bivoltine, 10 ; mono- voltine, 8 ; multivoltine, 12. Racks for silk trays, 33. Raw silk, importations of, 45. Reeling machine, Philippine, 42. Ricinus communis, 25. Roof of silk house, 33. bo S Sawali, use in silk house, 33. Scoured silk, 47. Scouring, 43. Second stage, 15. Sedeno, Antonio, 9. Selection of cocoons, improvement by, 39. Shade for silk house, 32. Shipping devices, Braine's, 41. Silk cocoons, color variations, 12. Silk culture, advantages of, 48 ; factors in, 47 ; profits in, 47. Silk elaboration, 42. Silk experts, 48. Silk house, 31, 46 ; accommodation, 34 ; essentials of, 32 ; number of silkworms to, 34 ; size of, 34. Silk, Japanese, 11 ; prices for, 47. Silk laboratory, 13. Silk markets, 48. Silk scouring, 43. Silk trade of the Philippines, 44. Silkworm eggs, experiments with, 11 ; to whom sent by Bureau of Science, 48. Silkworm first introduced, 9. Silkworm trays, 34. Silkworm, life-history of, 13 ; origin of, 8. Silkworms, amount of leaf required, 17 ; care of, in early stages, 14 ; habits of young, 13 ; handling of, 31 ; helplessness of, 14 ; how to feed, 15 ; introduction into Philippines, 7 ; number of trays required, 17 ; time in first stage, 14 ; transfer of, 14. Sinamay, use for silk house, 32. Site for silk house, 32. Soil, for mulberry, 35. Solenopsis geminata, 28. Spacing of racks, 34. Spiders, 28. Spinning apparatus, Philippine, for eri silk, 25. Spinning, devices for, 18 ; indications of, 18. Step-ladder, 34. Storage of leaf, 39. Sweeping in silk house, 34. Switzerland, reports from, on silk. 47. T Table for cutting leaf, 34. Table of leaf required, 17. Table of space required, 17. Talahib, for spinning, 18. Tangantangan, food for eri moth, 9. Termites, 32. Third stage, 16. Toyama, work of, with silkworms, 2'», 40. Tusser, wild, 27. Typhoons, dangers from, 34. u U. S. Department of Agriculture, mentioned, 42 ; quoted, 28. United States, reports from, on Philippine silk, 47. Value of imported silk, 44. Vidal, quoted, 9. w Wages of silk raisers, 46. Walls, construction of, 33. Wasps, 28. Weight of cocoons, 47. Wild silkworms, Philippine, 27 : foods of, 27. Winds, dangers from, 34. Women, adaptability for silk culture, 8. Yarns and threads of silk, importation of, 44. Yield of cocoons per hectare, 47. Yield of leaf per hectare, 47. Ylang-ylang, 27. Ylang-ylang moth, 8. Young silkworms, feeding of, 15. O — f • J-7 X r y - Vk.*^ \ - / N • *-. V- 1 75 ii i- ,7 ':::A Fig, 1, PLATE • 1 1 1 I M • i f i I # # I I * 1 911! M r I 1 ■ if i R 1 1 11 y« ESbtu'liF SIMS I f U i ■ 1 «r 1 ■ ft I * P ill fci "I" « P I « ^ ■ yi I gl ail| ft *is • f «fc% # ~T SCALE lOM B fM 0LATE XIX. L_ ./'^ ffil G> Rq 'V v /^ r I A / j l/\ ! \ , i! C .. :• i v ';> •j i ,-1 ^ S: • -! r si - i ? i ^> > ! ( ' ! ?! ; r"" i N i r ~ r^ r^" 3 ;^ > o S Ki H * J \ ! D \.. \ \x HI T HAND SILK-REELING MACHINE DIVISION OF ENTOMOLOGY BUREAU OF SClENCt MANILA X ./°..Z. . .-,,..„. :~»„ - .^,, ,^ ^^^ r ^^^m^^^J^tM^mmiim^2 > ^# v :r^,fy Order No. 41$. THE SUGAR INDUSTRY IN THE ISLAND OF NEGROS. By Herbert S. Walker. 145 pages, 10 photographic plates, and 1 map. Price $1.25 United States currency, postpaid. ABSTRACT OF CONTENTS. Page. Introduction; general and geographical information regarding Negros 9 Mountains, rivers, and climate 11 The sugar-producing districts of Negros 14 History of sugar production in Negros; varieties of cane grown in Negros; cane diseases and insect enemies; nationality of the planters; native labor; difficulties, past and present 16 The soil of Negros compared with that of other sugar-producing countries.. 68 Average composition of the purple or native sugar cane in Negros; other varieties of cane grown in Negros ; cane in the Haw r aiian Islands ; Egyptian cane; Java cane; Louisiana cane; West Indian cane; Negros as comr)ared with other countries in respect to the quality of cane; desirability of introducing other varieties of cane , 76 The cultivation of sugar cane and the production of sugar as carried on at the present time in Negros ; preparation of the soil ; preparation of the seed; planting; cultural operations after planting; cultivation of ratoon canes; period of growth of the cane; cost of cultivation; cutting the cane ; transporting the cane to the mill ; cost of cutting the cane and transporting it to the mill 82 Manufacture of sugar from the cane; extraction of the juice; manufacture of sugar from the juice; quality of the sugar produced in Negros; cost of manufacture; transportation and sale of the sugar; estimate of aver- age cost of same 02 Quantitative experiments to determine the weight of sugar produced from a given weight of cane 114 Calculation of the average cost of producing sugar in Negros by the methods now employed; cost for labor alone; estimate of fixed charges for main- tenance and depreciation of plant and interest on the capital invested; total cost of production 123 Possibilities for improvement; in cultivation; in manufacture; advantages of a change to modern methods of manufacture; the future of Negros; summary; appendix; an investigation to discover if diseases of the sugar cane exist in Negros 126 Index 143 NOTE. — Orders should be sent to the Business Manager, Philippine Journal of Science, Manila, or to any of the below-listed agents. Please give Order Number. FOREIGN AGENTS. ( The Macmillan Company, 64-66 Fifth Avenue, New York City, TJ. S. A. Messrs. Wm. Wesley & Son, 28 Essex Street, Strand, London, W. C, England. Mr. Martinus Nijhoff, Nobelstraat 18, The Hague, Holland. Messrs. Mayer & Muller, Prinz Louis Perdinandstrasse 2, Berlin, N. W., Germany. Messrs. Kelley & Walsh, Limited, 32 Raffles Place, Singapore, Straits Settlements. Messrs. A. M. & J. Ferguson, 19 Baillie Street, Colombo, Ceylon. CIRCULARS AND DESCRIPTIVE MATTER SENT ON APPLICATION. Order No. 411. INDO-MALAYAN WOODS. By Fred W. Foxworthy. (Being Section C, No. 4, Vol. IV, of the Philippine Journal of Science.) 182 pages, 9 photographic plates. Price $0.50 United States currency, postpaid. TABLE OF CONTENTS. I. Introduction. a. Erroneous popular notions with regard to eastern timbers. 6. Object of this work. c. Definition of the Indo-Malayan region. d. Eeview of previous work and acknowledgments. II. Properties of Wood. a. Woods of Tropics and Temperate regions compared. b. Weight and hardness, tables. c. Strength, work of Newton, Gamble and Gardner. d. Odor, color, taste. III. Suitability of different woods for special purposes. a. Enemies of wood. b. Woods exposed to salt water. c. Ship and boat building. IV. Rare, ornamental, or precious woods. Y. Comparative chart of common names. VI. Timbered areas and future supplies of wood. VII. Species notes. VIII. Index. _____ This valuable work is interesting both from the standpoint of com- mercial and scientific importance. As will be seen from the Table of Contents, the work treats exhaustively of the known Indo-Malayan woods. NOTE., — Orders should be sent to the Business Manager, Philippine Journal of Science, Manila, or to any of the below-listed agents. Please give Order Number. FOREIGN AGENTS. The Macmillan Company, 64-66 Fifth Avenue, New York City, U. S. A. Messrs. Wm. Wesley & Son, 28 Essex Street, Strand, London, W. C, England. Mr. Martinus Nijhoff, Nobelstraat 18, The Hague, Holland. Messrs. Mayer & Mtiller, Prinz Louis Ferdinandstrasse 2, Berlin, N. W., Germany. Messrs. Kelley & Walsh, Limited, 32 Raffles Place, Singapore, Straits Settlements. Messrs. A. M. & J. Ferguson, 19 Baillie Street, Colombo, Ceylon. CIRCULARS AND DESCRIPTIVE MATTER SENT ON APPLICATION. Order No. 407. THE BATAN DIALECT AS A MEMBER OF THE PHILIPPINE GROUP OF LANGUAGES. By Otto Scheerer. TOGETHEB WITH "F" AND "V" IN PHILIPPINE LANGUAGES. By Carlos Everett Conant. 141 pages. Price $0.80 United States currency, postpaid. Order No. 408. A VOCABULARY OF THE IGOROT LANGUAGE AS SPOKEN BY THE BONTOC IGOROTS. By Walter Clayton Clapp. Igorot-English and English-Igorot. 89 pages. Price $0.75 United States currency, postpaid. Order No. 102. A MANUAL OF PHILIPPINE BIRDS. By Eichard McGregor. Part 1-412 P ages| In twQ volumes Part 11—324 pages) Descriptions of all known species of Philippine birds, together with keys to species and genera. Price (for the 2 volumes) $4 United States currency, postpaid. NOTE. — Orders should be sent to the Business Manager, Philippine Journal of Science, Manila, or to any of the below-listed agents. Please give Order Number. FOREIGN AGENTS. The Macmillan Company, 64-66 Fifth Avenue, New York City, U. S. A. Messrs. Wm. Wesley & Son, 28 Essex Street, Strand, London, W. C, England. Mr. Martinus Nijhoff> Nobelstraat 18, The Hague, Holland. Messrs. Mayer & Miiller, Prinz Louis Ferdinandstrasse 2, Berlin, N. W., Germany. Messrs. Kelley & "Walsh, Limited, 32 Raffles Place, Singapore, Straits Settlements. Messrs. A. M. & J. Ferguson, 19 Baillie Street, Colombo, Ceylon. CIRCULARS AND DESCRIPTIVE MATTER SENT ON APPLICATION. Order No. 405. STUDIES IN MORO HISTORY, LAW, AND RELIGION. By Najeeb M. Saleeby. 107 pages. 16 illustrations. 5 diagrams. A Treatise on the history and customs of the Moro People. Price $0.25, United States currency. Order No. 408. A VOCABULARY OF THE IGOROT LANGUAGE AS SPOKEN BY THE BONTOC IGOROTS. By the Eev. Walter Clayton Clapp. Igorot-English and English-Igorot, Price $0.75, United States currency. Order No. 103. A MANUAL OF PHILIPPINE BIRDS. By Eichard C. McGregor. 769 pages. In two parts. Descriptions of all known species of Philippine birds, together with complete keys to Species and genera. Price ( for the two volumes ) $4, United States currency. Any of the above-announced publications may be ordered from the Business Manager, Philippine Journal of Science, Manila, P. I., or from any of the agents listed on the cover of this Journal. Please give order number. The Philippine Journal of Science Edited by „ PAUL C. FREER, M. D., Ph. D. The "Philippine Journal of Science" is issued as follows: Section A. Chemical and Geological Sciences and the Industries, ,$2 United States currency per year. Section B. Medical Sciences, $3 United States currency per year. Section C. 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